Secondary Dominants

[AlphaMale]

What exactly are they and how do you use Secondary dominants with composing?

[fretlessman71]

Pick a chord.

Start a new chord a perfect fourth below the root.

Play it as a dominant seventh chord. Follow it with the chord you picked earlier. The 7 chord becomes the "five of the other chord".

[AlphaMale]

Haha yeah thats what I was thinking, thanks.

[DocBop]

Jazz quickie you can proceed any chord by it V7. So got a II chord and want more movement proceed it with it V. So a Dmi7 proceed it with A7. Gotz a couple bars of a chord backcycle V7 chords. B7 E7 A7 Dmi7. All CoF stuff.

[HaVIC5]

A related jazz quickie, you can preceed any dominant 7 chord by it's related II-7. So that progression becomes F#-7 B7 B-7 E7 E-7 A7 Dm

[EADG mx]

Or if you want to go really crazy, you could go around the whole cycle of 5ths (cycle of Resolving Dominants)

C7 F7 Bb7 Eb7 Ab7 Db7 F#7 B7 E7 A7 D7 G7

it's non-stop ii-V that never resolves.. or always resolves..

[AlphaMale]

Now do they have to be Major chords with dominant 7's? or can they be minor chords with dominant 7's also?

[onlyclave]

Originally Posted by AlphaMale

Now do they have to be Major chords with dominant 7's? or can they be minor chords with dominant 7's also?

Secondary dominants can only be a Major triad, Major with a b7 (Dominant 7), diminished triad and fully diminished 7 (viio7) chord.

Remember that they are seconday dominants and as such must have a dominant function. Minor chords don't have enough harmonic pull to act like that.

[Phil Smith]

Originally Posted by AlphaMale

Now do they have to be Major chords with dominant 7's? or can they be minor chords with dominant 7's also?

There's no such thing as a minor chord with a dominant 7th.

Also, you have a major chord, a specific enitity, namely a triad and you have a dominant 7th chord.

[EADG mx]

Half-diminished functions as a dominant as well.

[HaVIC5]

Originally Posted by EADG mx

Half-diminished functions as a dominant as well.

No. Example.

EDIT:

I stand corrected by my own example. A very weak example of a m7(b5) functioning as a dominant is the VII-7(b5) going to I. This never happens in jazz/popular music, but it can happen in the classical canon. Other than that, I really can't think of anything. Dominant function is defined by the tritone created between fa and ti of the target chord. This is the only kind of example where that can happen.

[Kelly Coyle]

Gm7b5 --> C7b9 --> F6

The tritone between Db and G isn't the same as the B and F in G7, but it is much stronger than a vanilla ii chord, and could be said to have a dominant function. I think that's how half diminished can have a dominant function.

[projectMalamute]

Originally Posted by Kelly Coyle

Gm7b5 --> C7b9 --> F6

The tritone between Db and G isn't the same as the B and F in G7, but it is much stronger than a vanilla ii chord, and could be said to have a dominant function. I think that's how half diminished can have a dominant function.

That's a minor II-V-I, except you are landing on a major chord. I suppose you could think of it as V/V-V-I. I wouldn't, but I suppose someone could.

You will see half diminished chords with a dominant function when they are really just dominant 9ths without the root. Me, I'd call such a chord a dominant 9th. Actually, I'd just call it a dominant, voiced 3-5-7-9.

[AlphaMale]

Originally Posted by Phil Smith

There's no such thing as a minor chord with a dominant 7th.

Also, you have a major chord, a specific enitity, namely a triad and you have a dominant 7th chord.

oops sorry I get it.

so it can never be a minor 7th chord?

[onlyclave]

Originally Posted by Kelly Coyle

Gm7b5 --> C7b9 --> F6

The tritone between Db and G isn't the same as the B and F in G7, but it is much stronger than a vanilla ii chord, and could be said to have a dominant function. I think that's how half diminished can have a dominant function.

The topic is secondary dominants. You won't find a half-diminished chord in a secondary dominant function. All you've done is draw out a II V I in F minor with a Piccardy Third on the tonic. That's just a diatonic progression.

[Pacman]

Originally Posted by AlphaMale

oops sorry I get it.

so it can never be a minor 7th chord?

No. A dominant chord must be, well, dominant.

[the_stone]

Any chord which is labeled as a "dominant," whether it's the natural V chord (as G is in C major), or a secondary dominant (such as V/V, or V/vi) must contain the leading tone, which is the note a half-step below the root of the chord of resolution. Additionally, the chord may contain a minor-7th above the root ("dominant 7th" refers to chord type, not an interval). So, in C major, the chord G-B-D-F contains the leading tone B, and the minor 7th F. The tritone between these two creates a strong dissonance which resolves in stepwise motion, with the B ascending to C, and the F descending to E. For a secondary dominant, you usually have to chromatically alter the leading tone. So, to get a V/V in C, you have to raise F-natural to F-sharp to spell D-F#-A-C. The F# resolves up to G, and the C resolves down to B.

That's why some half-diminished chords can function as dominants, and others can't. A chord consisting of B-D-F-A can resolve to C, but a chord spelled D-F-Ab-C can't function as a dominant to G in a ii-V-I progression (but it could resolve to Eb, since D is the leading tone in Eb-major). That's also why a minor-7th chord can't function as a dominant; there's no leading tone to exert the pull towards anything.

Also, they're called "dominants" because the first theorists who described them characterized them as "dominating the key."

[Michael Case]

Originally Posted by EADG mx

Half-diminished functions as a dominant as well.

Diminished chords serve as dominant. Half diminished are ii chords for minor.

Ex.

A-7b5 D7#9 G-7
ii V i

Of course there's probably some example of a half diminished serving as a dominant, but from what I've learned and seen half diminished don't serve a dominant function.

[Michael Case]

To answer the OP. All the info you've gotten is correct, but I like things simple so I'll try to lay it out in what I call "idiot speak."

A secondary dominant is a dominant chord that is NOT in the original key to the composition, leading to a chord.

In other words, the tune is in C Major, you have a I vi ii V progression which in C would be C major 7 A minor 7 D minor 7 G7.
Now you take the vi chord A minor 7 and make it an A7 which is the V7 chord of D minor. That is a basic example of secondary dominants. If you look through "The Real Book" you'll find many tunes where this is used.

[ryco]

But can't a half-diminished serve as a Dominate sub like EADG suggests?

Can't it be seen as a Dom without the root? It still contains the tritone to resolve to I or i.

Bø > C (or c)